MBA is a post graduate degree and to be eligible for MBA one needs a graduate degree in any stream, so yes you can do MBA once you complete your b.sc . For example to be eligible for CAT ( one of the entrance exam for mba ) Candidates need to have passed his/her Bachelors degree or its equivalent from a recognized board or university,.candidates need to have passed his/her qualifying exam with minimum of 50% marks or equivalent CGPA. For the candidates belonging to ST/SC/PWD category must have passed with minimum of 45% marks. So ,yes you will be definitely eligible for mba , once you complete your b.sc.
For more information about, mba entrance examination and their eligibility etc go through https://bschool.careers360.com/articles/top-mba-entrance-exams-you-must-take/amp